title: A new approach to the determination of airway resistance: interrupter technique vs. plethysmography.
abstract: OBJECTIVE
  To determine the agreement between interrupter resistance (Rint) and airway resistance (Raw) by plethysmography in order to verify the clinical applicability of the interrupter technique.
  
  
  METHODS
  The Rint technique was performed with the patients in a sitting position, during exhalation, with a nose clip and cheek support. Plethysmography was carried out in accordance with standard protocols. All measurements were taken prior to and after the administration of an inhaled bronchodilator via a metered dose inhaler with a spacer.
  
  
  RESULTS
  The study comprised 99 consecutive patients referred to the Porto Alegre Hospital de Clínicas, located in the city of Porto Alegre, Brazil, for pulmonary function testing. Patient ages ranged from 18 to 82 years, and 52 of the patients were women. In the patients with FEV1 ≥ 60% of predicted, there was good agreement between the methods (r = 0.8; intraclass correlation coefficient = 0.8). The Rint values were lower than were those of Raw by plethysmography in the patients with more severe disease. However, there was good agreement between Rint ≥ 4 cmH2O L(-1) s(-1) and Raw by plethysmography > 2.5 cmH2O L(-1) s(-1) (likelihood ratio > 8; kappa coefficient = 0.73).
  
  
  CONCLUSIONS
  In the patients with less severe disease, there was good agreement between Rint and Raw by plethysmography. The agreement between the two methods was also strong regarding the detection of an increase in Raw. The Rint technique is a potentially useful method for the evaluation of adult patients.
authors.affiliation: Department of Pulmonology, Porto Alegre Hospital de Clínicas, Universidade Federal do Rio Grande do Sul-UFRGS, Federal University of Rio Grande do Sul-Porto Alegre, Brazil. leandro@gritti.com.br
authors.forename: Leandro Antônio
authors.initials: LA
authors.lastname: Gritti
authors.forename: Sérgio Saldanha Menna
authors.initials: SS
authors.lastname: Barreto
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000402:Airway Obstruction / Q000175:diagnosis* / Q000503:physiopathology; D000403:Airway Resistance / Q000502:physiology*; D001938:Brazil; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010991:Plethysmography; D012129:Respiratory Function Tests / Q000379:methods*; D055815:Young Adult